To define the prevalence of total coronary occlusion in the hours after transmural myocardial infarction, we used coronary arteriography to study the degree of coronary obstruction in 322 patients admitted within 24 hours of infarction. Total coronary occlusion was observed in 110 of 126 patients (87 per cent) who were evaluated within four hours of the onset of symptoms; this proportion decreased significantly, to 37 of 57 (65 per cent), when patients were studied 12 to 24 hours after the onset of symptoms. Among 59 patients with angiographic features of coronary thrombosis, the thrombus was retrieved by Fogarty catheter in 52 (88 per cent) but was absent in seven (12 per cent false positive). Among an additional 20 patients without angiographic features of thrombosis, a thrombus was discovered in five (25 per cent false negative). Thus, total coronary occlusion is frequent during the early hours of transmural infarction and decreases in frequency during the initial 24 hours, suggesting that coronary spasm or thrombus formation with subsequent recanalization or both may be important in the evolution of infarction.

Complete occlusion of the infarct-related coronary artery is a frequent finding soon after Q-wave (transmural) myocardial infarction. We performed coronary arteriography to study the frequency of total coronary occlusion and of angiographically visible collateral vessels in 341 patients within one week of non-Q-wave myocardial infarction. In this cross-sectional study, 192, 94, and 55 patients underwent coronary arteriography within 24 hours of peak symptoms, between 24 and 72 hours after peak symptoms, and between 72 hours and seven days after peak symptoms, respectively. In the three groups, total occlusion of the infarct-related vessel was found in 26 percent (49 of 192), 37 percent (35 of 94), and 42 percent (23 of 55) of the patients, respectively (P less than 0.05). The presence of visible collateral vessels increased in parallel: 27 percent (52 of 192), 34 percent (32 of 94), and 42 percent (23 of 55), respectively (P less than 0.05). The frequency of subtotal occlusion (i.e., greater than or equal to 90 percent stenosis) decreased inversely: 34 percent (65 of 192), 25.5 percent (24 of 94), and 18 percent (10 of 55), respectively (P less than 0.05). Thus, in contrast to Q-wave infarction, total coronary occlusion of the infarct-related vessel is infrequently observed in the early hours of non-Q-wave infarction, but it increases moderately in frequency over the next several days. These cross-sectional data suggest that non-Q-wave infarction may be related to a preserved but marginal blood supply, which sufficiently disrupts the relation between the supply of and the demand for myocardial oxygen to cause tissue necrosis.

Forty patients were treated for cardiogenic shock secondary to acute myocardial infarction. Twenty-one (group 1) were treated with intraaortic balloon counterpulsation and 19 (group 2) were treated with counterpulsation and coronary artery bypass grafting. The groups were similar in age, incidence of previous infarction, initial hemodynamics and coronary anatomy. The in-hospital mortality between group 1 (52.4%) and group 2 (42.1%) was not significantly different. The difference in long-term mortality between group 1 and group 2 was substantially different (71.4% vs 47.3%). The subset of group 2 (n = 12) that underwent reperfusion and counterpulsation within 16 hours from the onset of symptoms of infarction had a lower mortality (25.0%) than the subset (n = 7) that underwent operation more than 18 hours after the onset of symptoms (71.4%). The long-term mortality in the subset of group 2 patients operated on within 16 hours after the onset of infarction was significantly different from that in group 1 (25.0% vs 71.4%, p less than 0.03). The data suggest that reperfusion with counterpulsation is more effective when carried out early. Patients who develop shock more than 18 hours after the onset of symptoms of infarction appear to benefit most if treated with counterpulsation alone.

Global and regional left ventricular function were assessed before and after surgical coronary reperfusion in 54 patients surviving anterior transmural myocardial infarction. Two groups were identified. Group I (n = 34) was treated within 4.8 +/- 0.7 (mean +/- standard deviation) hours of onset of symptoms of anterior transmural myocardial infarction, and Group II (n = 20) was treated 9.2 +/- 4.8 hours from the onset of symptoms (p less than 0.01). On study entry, the two groups were similar in all characteristics except global left ventricular ejection fraction (48 +/- 9 versus 42 +/- 13%, p less than 0.05). Regional ejection fraction was obtained by computer-assisted planimetry from ventriculographic tracings at end-systole and end-diastole. The anterior wall was divided into four equal segments from the apex (area 1) to base (area 4). Areas 2 and 3 defined the midportion of the anterior wall of the left ventricle. This yielded four fractional changes expressed as ejection fraction in percent. Global and regional ejection fractions (from apex to base) of the anterior wall significantly improved in Group I (from 48 +/- 9 to 55 +/- 11%; 7 +/- 17 to 18 +/- 20%; 12 +/- 14 to 25 +/- 18%; 25 +/- 15 to 38 +/- 17%; and 39 +/- 13 to 41 +/- 12%) (p less than 0.05, except for the basal area), but only to a minor degree in Group II (from 42 +/- 13 to 45 +/- 16%; 9 +/- 10 to 13 +/- 15%; 10 +/- 10 to 17 +/- 10%; 27 +/- 16 to 32 +/- 14%; and 37 +/- 10 to 36 +/- 13%) (all p values were not significant [NS] except for region 2). These data suggest significant enhancement of global function and regional wall motion in selected patients if surgical reperfusion is performed within 6 hours from the onset of symptoms of anterior infarction. Little improvement can be expected when the procedure is instituted later than 6 hours from peak symptoms, although improvement in some patients occurs if adequate collateral perfusion or nontotal left anterior descending coronary occlusion is present. In spite of functional improvements, some contractile deficit persisted throughout the period studied even when successful reperfusion was achieved early during evolving anterior transmural myocardial infarction.

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